Flame Retardants

This book focuses on the chemistry and applications of flame retardants for polymers and other materials. It starts with a description and types of flame retardants, as well as their properties and chemical structures, to include chlorine- and bromine-containing flame retardants, phosphorus-based flame retardants, nitrogen-based flame retardants, and silicones. Inorganic materials that serve as flame retardants, such as boron-based additives, graphenes, and others are discussed in detail.

In addition, the following subjects are discussed in detail:

• Flame retardant polymers
• The mechanisms of flame retardants, such as flame cooling, synergetic effects, degradation of flame retardants, and others
• Other flame retardant compositions, such as dripping inhibitors and smoke suppressants
• Testing methods for flame retardants, international standards, human health hazards, such as smoke toxicity and problems with wastes
• Synthesis and fabrication methods, as well as recycling methods
• The application of flame retardants to the coating material using 3D printing, reactive coating, and bulk addition methods
• Non-burning comonomers, foams, nanocomposites and bio-based materials
• Flame retardants with other textiles, such as wool and electrical applications such as batteries

Johannes Karl Fink is Professor of Macromolecular Chemistry at Montanuniversität Leoben, Austria. His industry and academic career spans more than 40 years in the fields of polymers, and his research interests include characterization, flame retardancy, thermodynamics and the degradation of polymers, pyrolysis, and adhesives. Professor Fink has published many books on physical chemistry and polymer science including A Concise Introduction to Additives for Thermoplastic Polymers (Wiley-Scrivener 2009), The Chemistry of Biobased Polymers, 2^nd edition (Wiley-Scrivener 2019), 3D Industrial Printing with Polymers (Wiley-Scrivener 2019) and The Chemistry of Environmental Engineering (Wiley-Scrivener 2020).

Preface xiii

1 Types of Flame Retardants 1

1.1 History of Organic Flame Retardants 1

1.2 Commercially Available Flame Retardants 3

1.3 Chlorine-Containing Materials 7

1.3.1 HET Acid 7

1.3.2 Dechlorane Plus 7

1.3.3 Chlordene 10

1.3.4 Tris(1,3-dichloroisopropyl) phosphate 10

1.3.5 Tris(2-chloroethyl) phosphate 11

1.4 Bromine-Containing Materials 11

1.4.1 Brominated Diphenyl Ethers 11

1.4.2 1,2-Bis(2,4,6-tribromophenoxy)ethane 13

1.4.3 Trioxohexahydrotriazine Compound 15

1.4.4 2,4,6-Tris(2,4,6-tribromophenoxy)-1,3,5-triazine 15

1.4.5 Pentabromodiphenyl ether 17

1.5 Phosphorus Flame Retardants 17

1.5.1 DOPO 18

1.5.2 Resorcinol bis(diphenyl phosphate) 19

1.5.3 Resorcinol bis(di-2,6-xylyl phosphate) 19

1.5.4 Phosphor Amides 20

1.5.5 Polyphosphate Ester Morpholides 20

1.5.6 Cyclic Phosphazenes 22

1.6 Boron Additives 23

1.6.1 Zinc Borate 23

1.6.2 Boron Compounds and Magnesium Hydroxide 28

1.6.3 Boron Compounds and Aluminum Trihydroxide 28

1.6.4 Boron/Phosphorus Polymer 29

1.6.5 Boron Phosphate 31

1.6.6 Boron-Containing Novolac Resins 32

1.6.7 Spirocyclic Boron Compounds 33

1.6.8 Boron Triazine 34

1.6.9 Boron Nitride 37

1.6.10 Azo-Boron Compounds 43

1.6.11 Isosorbide-Derived Boron and Phosphorus Materials 46

1.6.12 Boron Cyclophosphazene Derivatives 46

1.6.13 Cardanol DOPO and Boron-Doped Graphene 49

1.6.14 Boron Crosslinked Cellulose Nanofibrils 49

1.7 Silicones 51

1.7.1 Hydroxy Silicone Oil 51

1.7.2 Hydrogen-Containing Silicone Oil 54

1.7.3 Red Phosphorus and Alumina Trihydrate 55

1.7.4 Aluminum Hypophosphite and Expandable Graphite 55

1.7.5 Phosphaphenanthrene Compound 56

1.7.6 Phosphorus-Silicone-Nitrogen Ternary Flame Retardant 58

1.7.7 Calcium and Aluminium-Based Fillers 59

1.7.8 Macromolecular Charring Agent 60

1.7.9 Intumescent Flame Retardants 61

1.7.10 Chitosan-Based Nanocoatings 67

1.7.11 Lignin-Based Silicone 67

1.7.12 Silicone-Based Adhesive 68

1.7.13 Nanofillers 69

1.8 Molybdenum Compounds 69

1.9 Graphenes 70

1.9.1 Synergist for Intumescent Flame Retardants 70

1.9.2 Electrochemical Preparation 73

1.9.3 Phosphaphenanthrene Graphene Hybrid Flame Retardant 75

1.9.4 Phosphaphenanthrene Graphene Copolymer 75

1.9.5 Bio-Based Polyphosphonate and Modified Graphene Oxide 77

1.9.6 Black Phosphorene Graphene Composite 78

1.9.7 Waste Deoxyribonucleic Acid 78

1.9.8 Poly(ionic liquid) and Graphene 79

1.9.9 Copper Decorated Graphene 80

1.9.10 Lignin-Modified Carbon Nanotube Graphene 81

1.9.11 κ-Carrageenan Flame Retardant Microspheres 82

1.9.12 Phenethyl-Bridged DOPO and Graphene Nanosheets 83

1.9.13 Graphene Nanoplatelets 83

1.9.14 Aerogels 87

1.9.15 Poly(etherimide) Membranes 89

1.9.16 Chitosan-Graphene Coatings 89

1.9.17 Polymeric Flame Retardant Functionalized Graphene 90

1.9.18 Graphene Oxide Compositions 90

1.10 Flame Retardant Fillers 104

1.10.1 Mineral Fillers 104

1.10.2 Melamine Phosphate Compounds 104

1.11 Admixed Additives 105

1.11.1 Phosphorus-Based Flame Retardant Fillers 108

1.11.2 Thermal Conductive Fillers 109

1.11.3 Organo-Modified Bentonites 110

1.11.4 Nanofillers 110

1.12 Bound Additives 111

1.12.1 Vinyl Ester Resin Monomer 112

1.12.2 Flame Retardant and Ester Curing Agents 112

1.12.3 DOPO Dicyandiamide 114

1.12.4 Mixed Flame Retardants 114

References 118

2 Mechanisms of Flame Retardants 131

2.1 Flame Cooling of Halogens 131

2.1.1 Antimony Trioxide Synergism 131

2.2 Halogen-Free Flame Retardants 132

2.2.1 Poly(propylene)Wood Plastic Composites 132

2.2.2 Diphenolic Acid-Based Biphosphate 133

2.2.3 Degradation of Triphenyl Phosphate 135

2.2.4 Phosphite-Silica Synergism 136

2.3 Benzoxazine Resin with Triazine Structure 137

2.3.1 Flame Retardant Carrageenan Fiber 138

2.3.2 Modified Silica Sol 140

2.3.3 DOPO-Based Triazole 140

2.3.4 DOPO-Based Tetrazole 143

2.3.5 Phosphor Nitrogen-Containing Compound 144

2.3.6 Polyheptazine/PA6 Nanocomposites 144

References 145

3 Dripping Inhibitors 147

3.1 Measurement Methods 147

3.2 Materials 149

3.2.1 PTFE Powder 149

3.2.2 Support for Polyester 150

3.2.3 Support for Poly(lactic acid) 159

3.2.4 Support for Poly(urethane) Foams 160

References 161

4 Smoke Suppressants 165

4.1 Materials 166

4.1.1 Zinc Borate and Aluminum Trihydrate 166

4.1.2 Zinc Hydroxystannate 168

4.1.3 Low-Melting Sulfate Glasses 170

4.1.4 Iron Oxide 170

4.1.5 Zinc Oxide 172

4.1.6 Ferrites 173

4.1.7 Bromide-Intercalated Hydrotalcite 176

4.1.8 Borate-Intercalated Layered Double Hydroxide 176

4.1.9 Hot Melt Adhesive Composition 177

4.1.10 Functionalized Graphene Oxide 178

4.1.11 Expandable Graphene 179

4.1.12 Modified Ammonium Poly(phosphate) for Thermoplastic PU 180

4.1.13 Glass Microspheres with Ammonium Molybdophosphate for Thermoplastic PU 180

4.1.14 Phosphorus-Containing Polyol for PU Foam 181

4.1.15 Porous Silicon Dioxide PU Foams 183

4.1.16 Sepiolite-Based Nanocoating for PU Foam 184

4.1.17 Abandoned Molecular Sieve for PU 184

4.1.18 Melamine Octamolybdate 185

4.1.19 Cardanol-Derived Zirconium Phosphate 185

4.1.20 Montmorillonite Nanocomposites 187

4.1.21 Waste Printed Circuit Boards 188

4.2 Special Applications 189

4.2.1 Diesel Fuel Filters 189

4.2.2 Electrical Cables 190

References 192

5 Standards and Testing 195

5.1 Abbreviation Standard for Chemicals 195

5.2 Test Procedures 197

5.2.1 Bromine-Based Flame Retardant Determination 197

5.3 Hazard Assessment 200

5.3.1 Human Health Hazards 200

5.3.2 Tetrabromobisphenol A 206

5.3.3 Phosphorus Flame Retardants 207

5.4 Standards 209

5.4.1 Test for Flammability 209

5.4.2 Ignition Characteristics of Plastics 209

5.4.3 Heat Release Rate 212

5.4.4 Smoke Toxicity 213

5.4.5 Smoke Density 213

5.4.6 Electrical or Optical Fiber Cables 214

5.4.7 Textiles 214

5.5 Life Cycle Sustainability of Flame Retardants 215

5.5.1 Life Cycle Method 215

5.5.2 Electronic Applications 221

5.5.3 Textile Products 222

5.5.4 Phenolic Resin with Brominated Flame Retardant 222

References 223

6 Synthesis and Fabrication Methods 229

6.1 3D Printing 229

6.2 Mechanochemical Phosphorylation 230

6.3 Coating Methods 231

6.3.1 Reactive Coating 231

6.3.2 Bulk Addition 231

6.4 Recycling 232

6.4.1 Brominated Flame Retardants 232

6.4.2 Enzymatic Recycling 235

6.4.3 Waste Melamine Formaldehyde Foam 236

References 236

7 Examples of Polymers 239

7.1 Poly(amides) 239

7.2 Nylons 240

7.2.1 Halogen-Containing Products 241

7.3 Poly(phenylene ether) Resins 245

7.4 Brominated Poly(phenylene ether) 246

7.5 Unsaturated Poly(ester)s 247

7.6 Epoxide Resins 248

7.7 Poly(carbonate) 249

7.8 Halogen-Free Flame Retardant Polymers 250

7.8.1 Organophosphorus Monomers 251

7.8.2 Epoxy Compounds 251

7.8.3 Poly(vinyl alcohol) 253

7.8.4 Poly(4-hydroxystyrene) 254

7.8.5 Poly(phosphate ester)s 256

7.9 Silicones 257

7.9.1 Degradation Mechanism 257

7.9.2 Halogen-Free Flame Retardant Silicone Rubber 258

7.9.3 Silicone Thermoplastic Elastomer 259

7.10 Foams 260

7.10.1 Poly(styrene) Foams 260

7.10.2 Poly(urethane) Foams 264

7.11 Nanocomposites 287

7.11.1 Dispersion of Nanofillers 287

7.11.2 Clay Nanocomposites 288

7.11.3 Epoxy Nanocomposites 288

7.11.4 Poly(styrene) Nanocomposites 289

7.11.5 Poly(lactic acid)-Containing Nanomaterials 290

7.12 Cellulosic Materials 292

7.12.1 Silica Nanoparticles 292

7.12.2 Phytic Acid 293

7.12.3 Bio-Based Foams 294

References 295

8 Special Uses 303

8.1 Textiles 303

8.1.1 Environmental Issues of the End-of-Life Phase 303

8.1.2 Flame Retardant Poly(amide) 6 305

8.1.3 Flame Retardant Textile Finishes 306

8.1.4 Condensed Tannin 307

8.1.5 Reactive Phosphorus-Containing Flame Retardants 308

8.1.6 Textile Coatings 310

8.1.7 Flame Retardant Back Coating Layer for Historic Textile Fabrics 310

8.2 Flame RetardantWool 311

8.2.1 Flame Retardant Monomer 311

8.2.2 Phytic Acid Compositions 313

8.2.3 Sulfamic Acid 315

8.3 Compositions for Asphalt and Bitumen 316

8.3.1 Comprehensive Testing Program 316

8.3.2 Thermal Decomposition Rates 318

8.3.3 Mixed Flame Retardants 320

8.3.4 Nanoclays 321

8.3.5 Effects of Aging 322

8.3.6 Non-Flammable Grades of Asphalts 322

8.3.7 Composite Flame Retardant Asphalt 324

8.3.8 Layered Double Hydroxides 324

8.3.9 Warm-Mixed Flame Retardant Modified Asphalt Binder 325

8.3.10 Environmentally Friendly Flame Retardant 325

8.4 Batteries 327

8.4.1 Lithium-Ion Batteries 327

8.4.2 Lithium-Sulfur Batteries 336

8.4.3 Sodium-Ion Batteries 338

References 339

Index 345

Acronyms 345

Chemicals 350

General Index 358

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